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Objectives: Iatrogenic instability can result after hip arthroscopy due to capsular insufficiency, which can be avoided with an effective closure of the hip capsule. There is currently no consensus in the literature regarding the optimal quantity of sutures upon capsular closure to achieve maximal stability postoperatively. The objective of this study was to determine the strength of one-, two-, and three-suture constructs for hip capsular closure to resist external rotation and extension following a standard anterosuperior inter-portal capsulotomy (12 to 3 o’clock). Additionally, the degree of external rotation at which the suture constructs failed was recorded. Methods: Nine pairs (n = 18) of fresh-frozen human cadaveric hemi-pelvises underwent anterosuperior inter-portal capsulotomies, which were repaired with one, two, or three side-to-side sutures. Each hip was secured in a dynamic, biaxial testing machine and underwent a cyclic external rotation preconditioning protocol followed by external rotation to failure (Figure 1). The non-parametric version of the BIBD ANOVA analysis (Durbin test) was used to assess the primary hypothesis that different suture numbers are associated with different torque capacities. When the omnibus Durbin test was statistically significant, post-hoc comparisons were made using Conover’s method, and the Holm-Bonferroni method was used to control the type-1 error. Group medians and ranges were reported. Significance was set at p < 0.05. Figure 1. The hip was subjected to a cyclic external rotation preconditioning protocol, with the hip oriented in 10° of extension and under a constant axial compressive load of 5 N. Following cyclic loading, the hip was realigned to its starting position and was externally rotated to failure. Images 1 – 6 document the sequence of the failure mechanism of a two-suture capsular closure construct. Results: The failure torque of a one-suture hip capsular closure construct was significantly less than the three-suture construct. The failure torque for the one-suture construct was 67.4 N-m (range: 47.4 - 73.6 N-m). For two sutures, the failure torque was 85.7 N-m (range: 56.9 - 99.1 N-m) and for three sutures the failure torque was 91.7 N-m (range: 74.7 - 99.0 N-m). Repair constructs exhibited 36º (range: 22° - 64°) of external rotation at failure torque. Conclusion: The most important finding of this study was that three sutures provided the strongest biomechanical construct, demonstrating a median maximum torque of nearly 91.7 N-m. A three-suture construct was significantly stronger than one suture; however, there was not a significant difference between two- and three-suture constructs. Additionally, constructs failed at approximately 35° of external rotation, providing an important guideline for appropriate rehabilitation to protect the capsular repair in the early postoperative period. Reestablishing the native anatomy of the hip capsule following hip arthroscopy has been reported to result in improved outcomes and reduce the risk of iatrogenic instability. Therefore, an adequate capsular closure is important to restore proper hip biomechanics, and postoperative precautions limiting external rotation should be utilized to protect the repair. Figure 2. Boxplots of failure torques for the three different constructs (one, two, and three sutures). Dark horizontal lines represent the median, with the box representing the 25th and 75th percentiles.

Objectives: The purpose of this study was to assess the effect of sequentially cutting the posterolateral, anterolateral, posteromedial and anteromedial structures of the knee on rotational kinematics in the setting of intact cruciate and collateral ligaments. It was hypothesized that cutting of the iliotibial band (ITB), anterolateral ligament and lateral capsule (ALL/LC), the posterior oblique ligament (POL), and the posteromedial capsule (PMC) would significantly increase internal rotation and that the anteromedial capsule (AMC), and the popliteus tendon and popliteofibular ligament (PLT/PFL) when sectioned would lead to a significant increase in external rotation of the knee. Methods: Ten pairs (n = 20) of cadaveric knees were assigned to two sequential cutting groups (posterolateral-to-posteromedial and posteromedial-to-posterolateral). Specimen were subjected to 5 N-m of internal and external rotation torque at knee flexion angles 0° through 90° in the intact and after each cut state. Rotational changes were measured and compared to the intact and previous states following each cut. Results: Sectioning of the ITB significantly increased internal rotation at 60° and 90° by 5.4° and 6.2[[Unsupported Character - Codename ­]]°, respectively (after ALL/LC cut) and 3.5° and 3.8° (prior to ALL/LC cut) (Figure 1). At 60° and 90°, section of the ALL/LC produced significant increases in internal rotation of 3.1[[Unsupported Character - Codename ­]]° and 3.5°, respectively (after ITB cut) and of 0.5° (prior to ITB cut) (Figure 1). At 0°, section of the POL produced significant increases in internal rotation of 2.0° (ITB intact) and 1.8° (after ITB cut) (Figure 1). Sectioning the PLT/PFL complex significantly increased external rotation at 60° and 90° by 2.7° and 2.9°, respectively (prior to sectioning medial structures) and 2.2° and 2.7[[Unsupported Character - Codename ­]]°, respectively (after sectioning medial structures) (Figure 2). Sectioning the AMC produced significant increases in external rotation at 30°- 90° of flexion, however the magnitude of change was < 1° (Figure 2). Figure 1. Changes in internal rotation from the intact state during a 5 N-m internal rotation torque when sequentially cutting structures from lateral to medial (above) and medial to lateral (below). Figure 2. Changes in external rotation from the intact state during a 5 N-m external rotation torque when sequentially cutting structures from lateral to medial (above) and medial to lateral (below). Conclusion: Collectively the anterolateral corner structures had a primary role in internal rotational control of the knee from 60° to 90° of knee flexion. The ITB was the most significant primary stabilizer for internal rotation in ACL intact knees. The POL contributed to internal rotational control at full extension, while the PLT/PFL complex controlled external rotation of the knee at higher flexion angles (60° and 90°). Internal rotation control of the knee has been mainly attributed to the cruciate and collateral ligaments. This study delineates the primary and secondary roles of the ITB, the ALL/LC, POL and PLT/PFL to rotatory stability of the knee. As such, it provides new information about the understanding of rotational instabilities of the knee.

Objectives: Straight antegrade intramedullary nailing of proximal humerus fractures has shown promising clinical results. However, up to 36% of all humeri seem to be "critical types" in terms of the potential violation of the supraspinatus (SSP) tendon footprint by the ideal nail's[for full text, please go to the a.m. URL], Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2016)

Objectives: Lateral meniscal posterior root avulsions are commonly found with anterior cruciate ligament (ACL) tears. The purpose of this study was to investigate the biomechanical effects of lateral meniscal posterior root avulsions with and without intact meniscofemoral ligaments (MFLs), and with concurrent ACL tears, on lateral compartment contact mechanics. Methods: A controlled laboratory study was performed using ten nonpaired fresh-frozen cadaveric knees. Tekscan sensors were used to simultaneously measure contact area and pressure (Figure) in the lateral and medial compartments. Specimens were tested with 6 conditions (1: Intact; 2: Lateral meniscal posterior root avulsion; 3: Root avulsion and torn MFL; 4: Condition 3 with ACL tear; 5: Condition 4 with ACL reconstruction; 6: ACL reconstruction with root repair) at 5 flexion angles (0, 30, 45, 60, and 90 degrees), under a 1000 N axial load. Results: Compared to the intact state, condition 2 did not significantly alter lateral compartment contact area or pressure (p < 0.05). A significant decrease in contact area and increase in mean contact pressure occurred in condition 3. Conditions 4 and 5 (ACL tear and reconstruction of the ACL, respectively, both with deficient MFLs and lateral meniscal posterior root avulsion) also produced significantly lower contact areas than the intact condition (p < 0.05), and were not substantially different than Condition 3 (Figure). Changes in contact mechanics tended to be greater at increased flexion angles; for condition 3 at 0 and 90 degrees, contact area decreased 37% and 52% (95% CI [21,53] and [39,66], respectively) and mean contact pressure increased 55% and 87% (95% CI [33,76] and [59,114], respectively). Condition 6 (root repair with ACL reconstruction) was not significantly different from the intact state (p < 0.05). Conclusion: The meniscofemoral ligaments protect the lateral compartment from changes in contact mechanics in the setting of a lateral meniscal posterior root avulsion, whereas combined lateral meniscal root avulsion and deficient meniscofemoral ligaments leads to substantial changes. Concurrent ACL reconstruction and root repair restores contact area and mean contact pressure to the intact state.

Objectives: Recent publications have described significant variability in the femoral attachment and overall anatomy of the anterolateral ligament (ALL). Additionally, there is a paucity of data on its structural properties. The purpose of this comprehensive investigation was to provide quantitative data characterizing the anatomic and radiographic locations, and structural properties of the ALL to assist in the development of an evidence-based approach to anterolateral ligament reconstructions. Methods: In this descriptive laboratory study, identification of the ALL was performed by a combined outside-in and inside-out anatomic dissection of 15 nonpaired cadaveric knees. Quantitative anatomic relationships were made using a three-dimensional coordinate measuring device. The ALL attachments and additional structures were marked with radiopaque markers prior to obtaining true anteroposterior (AP) and lateral radiographs. Radiographic distances were subsequently made using a picture archiving and communications system program. Structural properties were characterized during a single pull-to-failure test in line with the ALL fibers using a tensile testing machine. Ultimate failure strength (N), stiffness (N/mm), and mechanism of failure were recorded for each specimen. All anatomic, radiographic, and biomechanical measurements were reported as mean values and 95% confidence intervals (95% Confidence interval (CI), Lower bound, Upper bound). Results: Anatomy. The ALL was identified as a thickening of the lateral capsule coming under tension with an applied internal rotation at 30° of flexion. Its femoral attachment was consistently located posterior and proximal to the lateral epicondyle (LE), 4.7 mm posterior and proximal to the fibular collateral ligament (FCL) attachment. The ALL coursed anterodistally to its anterolateral tibial attachment approximately midway between Gerdy's tubercle and the anterior margin of the fibular head, located 24.7 mm (95% CI, 23.3, 26.2) and 26.1 mm (95% CI, 23.9, 28.3) from each structure respectively. Radiography. On the AP view, the ALL originated on the femur 22.3 mm (95% CI, 20.7, 23.9) proximal to the joint line and inserted on the tibia 13.1 mm (95% CI, 12.3, 13.9) distal to the lateral tibial plateau. On the lateral view, the femoral attachment was 8.4 mm (95% CI, 6.8, 10.0) posterior and proximal from the lateral epicondyle. The tibial attachment was 19.0 mm (95% CI, 17.1, 20.9) posterior and superior from Gerdy's Tubercle. Structural Properties. The average maximum load during pull-to-failure was 175 N (95% CI, 139, 211) and the stiffness was 20 N/mm (95% CI, 16, 25). Failure occurred by four distinct mechanisms: ligamentous tear at the femoral (n=4) or tibial attachment (n=1), midsubstance tear (n=4) and bony avulsion of the tibial attachment (Segond fracture; n=6). Conclusion: In conclusion, the ALL was observed as a capsular thickening of the lateral knee, primarily coursing from an attachment posterior and proximal to the lateral femoral epicondyle to the anterolateral tibia which was confirmed by anatomic, radiographic and structural property methods. Failure mechanisms of the ALL included tearing at the femoral origin, intrasubstance tears, and bony avulsions of its tibial attachment (Segond fractures). If necessary, the ALL can be adequately reconstructed using most soft tissue grafts.